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What is a Plasma Cutter?

29th September 2016

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CNC plasma cutters have been used in the industry for all cutting purposes for the last 30 years; however, their use has become more widespread, especially in smaller establishments only quite recently.

While the output of plasma cutting itself is quite accurate and precise, there is a human element involved in the cutting process. Whereas, in the case of CNC plasma cutters, 3D sophisticated software creates predetermined designs while also controlling the cutting table process itself and the results are truly astonishing.

Why is a CNC Plasma Cutter Table Used?

A plasma cutter is commonly employed for cutting varied kinds of metals for various purposes. Plasma cutters are excellent tools for cutting through metal plates, sheet metal, bolts, pipes, etc. They also serve as excellent gouging tools to remove defective welds or gouging weld joints. These hand-held cutters can also be used for cutting small, intricate shapes from steel plates; however, it is very difficult to get complete accuracy or perfect quality of edges for most of the fabrications done by hand. This is when CNC plasma becomes a necessity.

A CNC plasma cutter is a system in which the plasma torch is moved by using computer commands. CNC stands for “Computer Numerical Control”, which means that numerical codes are used by a computer to give instructions and direct the movements of the cutter.

Parts of the CNC Plasma Cutter

The CNC is the actual controller for machine tools. It has an interface panel and a special control console, or it can simply be a Windows-based computer running a software program and giving commands to the machine drives. Most machines today use a laptop or a desktop computer to control the CNC plasma system.

The movement of the plasma cutter is directed by the CNC. A program with G-codes and M-codes describes the contours of the part and when the cutter should be turned on and off. These programs are created by software called post-processors that takes part geometry from a CAM file and translates it into the M-codes and G-codes that can be read and understood by the CNC plasma.

The CNC plasma cutter also needs a drive system including motors, amplifiers, encoders and cables. There are usually two motors — one for the X-axis and one for the Y-axis. The drive amplifier converts the low power signal from the CNC to a higher power signal that helps to move the motor. Each axis has an encoder, which is a feedback mechanism, which indicates the position of the axis and how far it has moved. The cables carry power from the amplifier to the motor and also carry position signals from the encoder to the CNC plasma system.

The CNC plasma reads the part program that has been input and outputs the signals to the machine’s drive system that moves the torch in the required direction at the pre-programmed speed. The CNC reads the encoder feedback and makes adjustments to the drive signals to keep the movement of the cutter on the desired path. The measurements and position information is updated every few milliseconds, which allows the machine’s movement to be smooth and accurate, so that the cuts are smooth, straight and the material has consistent edge quality and correct part dimensions.

The CNC plasma cutter also has an “input-output” system that turns on the plasma cutter at the appropriate time. It tells the CNC when the plasma has started and is ready to move. This is the most basic form of input and output, but more complex systems can be added to the existing one depending on the nature and requirement of the operations.

Today, with the fabrication requirements becoming more demanding and the processes becoming more complex, the CNC plasma cutter is definitely a “must have” piece of machinery in every fabricator’s arsenal.